Powders and granulated solids are used throughout industry. Wherever these materials are handled, they generate dust that can affect worker health, cause a safety problem, or cause a nuisance. The research proposed here will investigate fundamental factors that affect dust generation, and explore ways that dust generation can be controlled. This work will allow health and safety problems related to dust exposure to be assessed more knowledgeably, and to be reduced more efficiently. Factors that affect the rate dust is generated and its resultant size distribution (dustiness) are poorly understood. The proposed research will address this point through three objectives. (1) develop a test that measures dustiness, (2) use the test to understand factors that affect dustiness, and (3) evaluate measures by which dustiness can be controlled. The effects of material size distribution, drop height, moisture content, material flow, and amount of entrained air will be explored. In the work planned, granular material with measured characteristics will be dropped a known distance at a known rate. The mass and size distribution of the generated dust will be measured using a high-volume cascade impactor in an apparatus designed to capture all generated dust. The amount of air entrained in the falling material will also be measured. Results will be analyzed using theory that rests on fundamental understanding of phenomena that affect dustiness. The test to be developed can be used: (1) to set dustiness standards for materials used in industry, (2) to assess the inherent dustiness of processes and materials, important for the pre-manufacture notification requirements of TOSCA, and (3) to permit ready evaluation of changes to materials and processes that can control dust. The test will allow an easy, inexpensive way to characterize dust sources.